The exception has nothing to do with the signal or, indeed, with the player train.
The problem is related to an AI train.
My first guess is that an action 'signal' (like applying or releasing the brakes) is being passed down the train just as this train is removed.
Could you please run from the save again, this time enabling the Dispatcher info display (3x shift-F5), and check if an AI train is removed about the time the crash occured?
The exception has nothing to do with the signal or, indeed, with the player train.
The problem is related to an AI train.
My first guess is that an action 'signal' (like applying or releasing the brakes) is being passed down the train just as this train is removed.
Could you please run from the save again, this time enabling the Dispatcher info display (3x shift-F5), and check if an AI train is removed about the time the crash occured?
Thanks.